Search found 226 matches

by za909
Sat Feb 02, 2019 5:16 am
Forum: Other Retro Dev
Topic: PC Engine waveform channel updates
Replies: 8
Views: 20165

Re: PC Engine waveform channel updates

I have since tried to do the same on the FDS, a system where I know that the channel has to be halted and reset to change the waveform, and the results are oddly clear with very little artifacts added. This is a promising next step.
by za909
Sat Jan 05, 2019 2:32 am
Forum: Newbie Help Center
Topic: Help understanding sprite-0
Replies: 23
Views: 8562

Re: Help understanding sprite-0

A slightly less complicated, but also less effective way to "get more colors" is to use the PPU color emphasis bits . It's not nearly as useful as an actually changed palette, but it lets you get a few more tones (or a few washed-out colors by combining them with the grayscale bit) out of your alrea...
by za909
Thu Nov 22, 2018 3:45 am
Forum: NESdev
Topic: Interleaving on the NES
Replies: 7
Views: 5780

Re: Interleaving on the NES

As it turns out, my original guess of being able to save 100-150 cycles was an extremely generous assumption. Currently, in the middle of redesigning the PCM code to accomodate this interpreter, it seems that the interpreter needs to be aware of how many cycles it has to spend before it has to retur...
by za909
Tue Nov 20, 2018 1:57 am
Forum: SNESdev
Topic: Need sound help emulating NES on SNES
Replies: 33
Views: 27628

Re: Need sound help emulating NES on SNES

Some games do attempt to silence the triangle channel in weird ways that might cause some issues: - Mega Man and Mega Man 2, plus other Capcom games from around that time silence the triangle by writing 0 to the period register, some even use $4015 afterwards, it's really odd, but it makes a popping...
by za909
Wed Nov 07, 2018 5:16 am
Forum: Newbie Help Center
Topic: Trying to understand PPU Registers
Replies: 15
Views: 7004

Re: Trying to understand PPU Registers

Your decoder has to look at the right bits (pins) to determine when to enable the peripheral and allow traffic between the CPU and the peripheral. My super simple 64kB PRG ROM setup requires a 1-bit register to select which 32kB half of the ROM I want the system to see at $8000-$FFFF. Since $8000-$F...
by za909
Wed Nov 07, 2018 3:35 am
Forum: NESdev
Topic: Interleaving on the NES
Replies: 7
Views: 5780

Re: Interleaving on the NES

Possible tasks that could be made to run in constant time: * Filling buffers for scrolling * Filling buffers for sprites Thanks for the ideas. Thankfully I wouldn't even have scrolling updates because the rooms would be non-scrolling screens with fadeouts for transitioning, where the game draws the...
by za909
Tue Nov 06, 2018 2:36 pm
Forum: NESdev
Topic: Interleaving on the NES
Replies: 7
Views: 5780

Interleaving on the NES

I have a long-going project to use the DMC IRQ to stream PCM data at 8.2kHz while still having enough time to run a game (with the tasks spread out across two frames for 30FPS). However, this is done by sitting around in the IRQ handler so that I can land another $4011 write right in between two IRQ...
by za909
Fri Oct 05, 2018 1:33 am
Forum: NESdev
Topic: Problem converting 256 KB MMC-1 to 512 KB MMC-1
Replies: 55
Views: 15954

Re: Problem converting 256 KB MMC-1 to 512 KB MMC-1

That makes sense, it's a way to assess how far people have come with reverse-engineering the hardware if you try to stick to the same limits on hardware as developer X, but you are still able to do more thanks to discoveries since then, and more time to spend on managing the available resources bett...
by za909
Thu Oct 04, 2018 3:26 am
Forum: NESdev
Topic: Fun with strange bugs!
Replies: 22
Views: 8999

Re: Fun with strange bugs!

It just happens too often that you accidentally end up using zero page memory access instead of an immediate value. Had the 6502 assembly language been originally developed to require you to prefix both immedate values and memory accesses, this kind of mistake would slip through much less often. Whe...
by za909
Wed Oct 03, 2018 7:24 am
Forum: NES Graphics
Topic: what does 8 bit graphics mean
Replies: 43
Views: 34253

Re: what does 8 bit graphics mean

When someone says NES "framebuffer", I immediately think of Videomation and Oeka Kids , which are designed to store a full screen framebuffer in CHR RAM. After that, I think of pseudo-framebuffers as used in Qix , Hatris , the Block Out prototype, 3D Block , and the like. If I'm not mistaken, it co...
by za909
Wed Oct 03, 2018 5:19 am
Forum: NES Graphics
Topic: what does 8 bit graphics mean
Replies: 43
Views: 34253

Re: what does 8 bit graphics mean

I have more of a pet peeve with people who call every chip in a system a "processor" as if you can't just make circuitry that does it's specific job by itself and has to execute code. Nowadays pretty much every chip is a processor of some kind, but back in the 80s and 90s, that wasn't the case. I f...
by za909
Wed Oct 03, 2018 3:30 am
Forum: NES Music
Topic: OptoSound (NES Music Engine)
Replies: 7
Views: 8943

Re: OptoSound (NES Music Engine)

It doesn't have to be famitracker per se. Some people like MML so as long there is a way to write music other then putting bytes manually to create music then it should be fine. The only reason I mentioned famitracker is with a system like that, for people that don't know about music, I can make si...
by za909
Wed Oct 03, 2018 3:07 am
Forum: NESdev
Topic: Fun with strange bugs!
Replies: 22
Views: 8999

Re: Fun with strange bugs!

I can tell you that I'm way too obsessed about coding mistakes to just roll back and carry on when something seemingly unrelated breaks! Whenever that happens to me, I spend as much time as it takes to figure out *exactly* what went wrong, otherwise something even more sinister may end up happening...
by za909
Mon Sep 24, 2018 2:47 am
Forum: NES Music
Topic: Poll, What music driver do you use?
Replies: 15
Views: 24389

Re: Poll, What music driver do you use?

Famitracker (0CC fork by Hertzdevil) for quick compositions. If I'm working on a homebrew, or other project then I always stick to writing my own unless someone else is in charge of the project and wants to go for a particular driver.
by za909
Tue Sep 04, 2018 10:45 am
Forum: NESdev
Topic: MM3 scanline counter, check multiple point possible and how?
Replies: 44
Views: 13429

Re: MM3 scanline counter, check multiple point possible and

If you have a different IRQ system for different parts of your game it is pretty useful to set up multiple IRQ handlers in software by pointing the IRQ vector at RAM, where you place a JMP absolute (hex: $4C) instruction when initializing the console, and then the two byts after it will be used as t...